The Internet enables a user of a client computer system to identify and communicate with millions of other computer systems located around the world. A client computer system can identify each of these other computer systems using a unique numeric identifier for that computer called an “IP address.” When a communication is sent from a client computer system to a destination computer system, the client computer system typically specifies the IP address of the destination computer system in order to facilitate the routing of the communication to the destination computer system. For example, when a request for a World Wide Web page (“Web page”) is sent from a client computer system to a Web server computer system (“Web server”) from which that Web page can be obtained, the client computer system typically includes the IP address of the Web server.
In order to make the identification of destination computer systems more mnemonic, a Domain Name System (DNS) has been developed that translates a unique alphanumeric name for a destination computer system into the IP address for that computer. The alphanumeric name is called a “domain name.” For example, the domain name for a hypothetical computer system operated by Example Corporation may be “comp23.example.com”. Using domain names, a user attempting to communicate with this computer system could specify a destination of “comp23.example.com” rather than the particular IP address of the computer system (e.g., 198.81.209.25). Domain names may include character sets such as upper and lowercase letters a-z and digits 0-9. Internationalized Domain Names are domain names that include characters used in the local representation of languages that are not written with the twenty-six letters of the basic Latin alphabet “a-z”. An IDN can contain Latin letters with diacritical marks, as required by many European languages, or may include characters from non-Latin scripts such as Arabic or Chinese. Many languages also use other types of digits than the European “0-9”. The basic Latin alphabet together with the European-Arabic digits are, for the purpose of domain names, termed “ASCII characters” (ASCII=American Standard Code for Information Interchange). These are also included in the broader range of “Unicode characters” that provides the basis for IDNs.